L. A. Bauer— Variation of Terrestrial Magnetism. 208 
subject to the laws of such a system, I have drawn on the dia- 
gram (p. 199) the lines connecting the places of maximum west 
and east declination along parallelsof latitude. These lines are 
indicated thus: The one on the left connects the 
places of maximum easterly declination ; the other, skirting the 
west coast of Africa, passes through the places of maximum 
westerly declination. If the foregoing deduction is true that 
the secondary system causes the deflection of the declination 
needle, then since the horizontal intensity component of the sec- 
ondary system is a maximum along the secondary magnetic 
equator, the lines of maximum declination should follow some- 
what the zero isapoclinies.. It will be noticed that this is 
roughly true. Exact coincidence must not be expected, since 
the magnetic intensity equator and dip equator do not neces- 
sarily fall together on account of the complexity of the sec- 
ondary system. 
Let us compare roughly the maximum horizontal intensities 
of the two systems. For the total uniform system we obtain 
the maximum value of 0°330 C. G. 8S. in the geographical 
equator (see table, p. 196). 
If we resolve the observed horizontal component in the 
geographical equator into two components, one directed due 
north (X component) and the other, directed west (Y compo- 
nent) we shall get these values near the secondary magnetic 
equator : 
Long. x ¥, = 
40° W. 293 +049 6°0 
200 W. "276 +°106 2°6 
0 "283 +°097 2°9 
20 Hy "293 +°069 4°3 
160 K. °365 —°047 7°8 
180 364 —°056 6°5 
160 W. 357 —°041 hat 
Mean 5°6 
Or, the polar field is on the average about 5 or 6 times 
stronger than the equatorial. Jn other words, if the magnetic 
moment of the resultant system be taken as 0:330Xa*, that of 
the primary is roughly, 0-325xa, and of the secondary 
0-060 Xx a’. 
In consequence of this secondary magnetic moment attached 
to the primary, roughly at right angles, the axis of the 
resultant magnetic system must incline towards the equator 
by an amount w computed thus: 
